This invention relates to compounds and methods for treating prostaglandin E mediated diseases, and certain pharmaceutical compositions thereof. More particularly, the compounds of the invention are structurally different from NSAIDs and opiates, and are antagonists of the pain and inflammatory effects of E-type prostaglandins.
Three review articles describe the characterization and therapeutic relevance of the prostanoid receptors as well as the most commonly used selective agonists and antagonists: Eicosanoids: From Biotechnology to Therapeutic Applications, Folco, Samuelsson, Maclouf, and Velo eds, Plenum Press, New York, 1996, chap. 14, 137-154; Journal of Lipid Mediators and Cell Signaling, 1996, 14, 83-87; and Prostaglandins and Other Lipid Mediators, 2002, 69, 557-573.
Thus, selective prostaglandin ligands, agonists or antagonists, depending on which prostaglandin E receptor subtype is being considered, have anti-inflammatory, antipyretic and analgesic properties similar to a conventional non-steroidal anti-inflammatory drug, and in addition, have effects on vascular homeostasis, reproduction, gastrointestinal functions and bone metabolism. These compounds may have a diminished ability to induce some of the mechanism-based side effects of NSAIDs which are indiscriminate cyclooxygenase inhibitors. In particular, the compounds are believed to have a reduced potential for gastrointestinal toxicity, a reduced potential for renal side effects, a reduced effect on bleeding times and a lessened ability to induce asthma attacks in aspirin-sensitive asthmatic subjects.
In The Journal of Clinical Investigation (2002, 110, 651-658), studies suggest that chronic inflammation induced by collagen antibody injection in mice is mediated primarily through the EP4 subtype of PGE2 receptors. Patent publications U.S. Pat. No. 5,965,741 (Oct. 12, 1999), U.S. Pat. No. 5,811,459 (Sep. 22, 1998) and EP 0752421-B1 (Oct. 12, 2005) disclose compounds as being useful in the treatment of prostaglandin mediated diseases.
The present invention is directed to novel compounds that are antagonists of the EP4 subtype of PGE2 receptors. The compounds would therefore be useful for the treatment of diseases or conditions mediated by the EP4 receptor, such as acute and chronic pain, inflammation, osteoarthritis, and rheumatoid arthritis.